The invention relates to a cleaning head for a floor cleaning device with a rotatable brush roller which is coupled to a drive motor via an overload coupling, wherein the overload coupling transfers only a limited torque.
Cleaning heads of this type are used for floor cleaning devices, with the aid of which a floor surface to be cleaned can be cleaned, for example, can be brushed and vacuumed. The cleaning head comprises a rotatable brush roller which can be driven by a drive motor. An overload coupling is connected between the brush roller and the drive motor and this transfers only a limited torque. As a result, it is ensured that the transfer of torque is interrupted by the overload coupling when a predetermined limiting value is exceeded. Such an interruption occurs, in particular, when the rotation of the brush roller is blocked. On account of the overload coupling, the drive motor can continue to run uninterrupted and without it becoming overloaded even in the case of such a blocking of the brush roller.
Overload couplings are also designated as torque limiters or overload protection devices and are known as such from EP 0 108 930 B1. Torque can be transferred between two machine elements with their help, wherein this transfer is, however, interrupted when an overload occurs, i.e., when a maximum limiting value of the torque is exceeded. As a result, it may, for example, be ensured that the drive element is not damaged during any blocking of the driven element.
An overload coupling is known from DE 29 34 164 A1, with which several coupling elements in the form of steel balls are held in their coupling position, in which they transfer torque from the drive element to the driven element, by means of a thrust sleeve spring-loaded in axial direction. When an overload occurs, the thrust sleeve is acted upon by the steel balls with a thrusting force effective in axial direction so that it is deflected in an axial direction and, as a result, facilitates a radial movement of deflection of the steel balls, wherein the transfer of the torque is then interrupted. The overload coupling known from DE 29 34 164 A1 is of a complicated construction.
An overload coupling is known from U.S. patent specifications No. 3,552,147 and No. 2,730,220 which has a drive element and a driven element which are arranged concentrically to one another, thereby forming an intermediate space. The intermediate space accommodates a coupling element which transfers torque, wherein the coupling element can be moved from the intermediate space into an alternative space contrary to the action of an elastic restoring force when an overload occurs. The overload coupling also has an overload element which is spring-loaded in the direction of rotation of the coupling element and releases the alternative space for the coupling element when an overload occurs.
The object of the present invention is to further develop a cleaning head for a floor cleaning device of the type specified at the outset in such a manner that the overload coupling has a constructionally simple design, can be produced inexpensively and can be operated reliably.